Sterling County is in western Texas, bordered on the east by Coke County, on the south by Tom Green County, on the west by Reagan and Glasscock counties, and on the north by Howard and Mitchell counties. The center of the county lies at 31°50' north latitude and 101°03' west longitude, thirty-seven miles southeast of Midland. The area was named for W. S. Sterling, a buffalo hunter, rancher, and Indian fighter who may have been the first permanent settler in the area. Sterling County covers 914 square miles of the central prairie, is surrounded by hills, and drains to the North Concho River and its tributaries-Sterling, Ross, and Crystal creeks. Soils vary from sandy to black. Elevations in the area range from 2,200 to 2,600 feet above sea level. Annual rainfall averages nineteen inches. Temperatures range from an average minimum of 33° F in January to an average maximum of 95° F in July; the growing season lasts 224 days. In the 1980s 96 percent of the county's area was in farms and ranches. In the early 1980s the agricultural sector of the county's economy earned an average annual income of $7.5 million, nearly all of which was derived from beef cattle, sheep, and goats; crops such as wheat, barley, hay, and pecans were also grown in Sterling County. There is no manufacturing in the area, but oil and gas production are important to the local economy. In 1982, 2.5 million barrels of oil were produced in the county, earning $75 million, and by January 1, 1991, 286,548,000 barrels of crude had been produced in Sterling since 1947, when oil was discovered there. U.S. Highway 87 (north-south) takes residents of the county to Big Spring, while State Highway 158 (east-west) provides easy access to Midland. State Highway 163 (north-south) also runs through the county.
In the eighteenth and nineteenth centuries the hunting grounds around the North Concho were used by Comanches, Lipans, Kiowas, and Kickapoos, all of whom maintained the rich material culture of plains tribes. The region was within a land grant made by Sam Houston in 1842 to Henry F. Fisher and Burchard Miller (see FISHER-MILLER LAND GRANT), but apparently no settlement in what is now Sterling County resulted. Fur traders, Texas Rangers, and federal troops passed through the area between 1800 and 1860. As elsewhere in the region settlement began after the Civil War, when the United States Army pushed the Indians to the west, and the buffalo herds were destroyed. Among the earliest settlers in the area were W. S. Sterling and S. J. Wiley, both buffalo hunters. According to legend, Frank and Jesse James hid out on Sterling Creek in the 1870s to raise horses and hunt buffalo. Fort Concho (first called Camp Hatch, then Camp Kelly) was established by the United States Army in 1867. Camp Elizabeth, an outpost of Fort Concho near the site of present Sterling City, protected ranchers who moved into the area during the 1870s. Huge spreads appeared in the area, such as the Half Circle S, established by the Peacock brothers; the MS, set up by Schuster, Henry, and Company; and the U Ranch, established by D. A. Earnest and W. J. Holland. In early days cattle were driven to Colorado City and occasionally as far as Fort Worth. Despite the importance of ranching for the early settlement of the area, the huge ranches lasted in what is now Sterling County only until the mid-1880s. By that time, homesteaders were competing with ranchers for land.
The land use patterns of West Texas were revolutionized by state homestead laws, which helped settlers challenge ranchers use of large spreads of public lands. School and railroad land was available at one to three dollars an acre, and a buyer could acquire as many as seven sections. Some ranchers resisted the movements and claims of homesteaders, but their resistance was short-lived. The drought of 1883 precipitated the fence-cutting wars, a particularly violent phase of this change in land use. Fence cutters sometimes failed to distinguish between ranchers who enclosed their own lands with barbed wire and those who enclosed public lands within their legitimately held lands. Statewide, there were three killings associated with fence cutting; property damages amounted to $20 million in 1883, leading to state legislation the next year prohibiting both fence cutting and the enclosure of public lands. The arrival of homesteaders in Sterling County precipitated the breakup of some of the great free-range ranches; the drought of 1886–87, which bankrupted the Half Circle S, helped to hasten their demise. Camp Elizabeth was abandoned in 1886.
When the county was established and organized in 1891 from Tom Green County, it already included eight or ten small communities, several of which had post offices and schools. A spirited contest between Sterling City and Commins (Cummins) for the county seat was fueled by the local newspapers, the Sterling Courier and the North Concho News. When the county's voters chose Sterling City as the county seat, Cummins did not survive. As the 1890s progressed populism became a contentious issue in county politics; according to one source, the population was almost evenly divided between Populists and Democrats. In spite of their divisions on other issues, however, the voters could agree on the necessity to prohibit the sale of liquor in the area; in 1898 the county was voted dry. By 1900 there were eighty-six farms and ranches, encompassing 425,655 acres, in Sterling County, and 1,127 people lived there. Though small areas in the county were beginning to be cultivated, stock ranching dominated the local economy. Only 3,129 acres in the county was classified as "improved" that year. Meanwhile, 17,000 cattle grazed on county pastures. Sheep, introduced to the area about 1890, numbered 1,400 by 1900. Initial farming efforts were limited to growing sorghums, oats, and cane for livestock feed; there was also a little truck farming to satisfy local needs. Cotton was first planted in 1889, and Sterling City opened its first gin in 1895; others were established later. By 1900, 136 acres was planted in cotton, and by 1910 production of the fiber had expanded to 1,626 acres. When the Santa Fe Railroad reached Sterling City from San Angelo in 1910, there were 135 farms and ranches in the county, and the area's population had increased to 1,403. Hopes that farming in the area might blossom into a cotton boom faded, however, as it became apparent that county lands were most suitable for grazing. The cotton gins eventually failed; by 1920 only 650 acres in Sterling County was planted in cotton. Hundreds of people left the area in the 1910s, so that by 1920 only 1,053 people remained.
Though farmers found the area generally inhospitable to cultivated crops, ranching continued to expand in the county. The number of sheep grew to 59,000 by 1920 and to 118,000 by 1930; the number of cattle also grew, and in 1930 the agricultural census reported 25,000 head in the area. Sterling County experienced a brief boom when the number of farms and ranches in the area increased from 131 in 1920 to 176 by 1925. By 1930 the number had tapered off to 136 farms and ranches, almost exactly the same number as had existed in the county twenty years before. The population of the county nevertheless rose by 30 percent during the 1920s, reaching 1,431 by 1930. By this time, most of the county's early communities were fading away, and the population was increasingly centered in Sterling City. The county's economy declined during the Great Depression of the 1930s. While the number of sheep in the area increased to 147,000 by 1940, the number of cattle declined by 50 percent during the 1930s, dropping to 11,000 by 1940; meanwhile, the number of farms and ranches in the area also declined significantly. By 1940 there were only 117 agricultural holdings in the area, and the population of the county had declined to 1,404.
Oil was discovered in Sterling County in 1947 and helped to bail out the area's declining economy. Petroleum production in the county rose from 17,309 barrels in 1948 to 861,000 barrels in 1956, to 920,00 barrels in 1960, and to 1,946,000 barrels in 1965. Production declined to 937,000 barrels by 1974, but soon revived to 1,965,000 barrels in 1978 and 2,565,000 barrels in 1982. In 1990, 2,455,579 barrels of crude were taken from county lands. Despite the developing oil and gas industry, the population of the county declined from the 1940s to the 1960s, dropping to 1,262 by 1950 to 1,177 by 1960 and to 1,056 by 1970. The number of people living in the county began to increase during the 1970s, however, and rose to 1,206 by 1980 and to 1,438 by 1990. As of 2014, 1,339 people lived in the county. About 59.3 percent were Anglo, 1.4 percent African American, and 37 percent Hispanic. The voters of Sterling County supported the Democratic candidates in virtually every presidential election between 1892 and 1964; the only exception occurred in 1952 and 1956, when a majority of the county's voters backed Republican Dwight D. Eisenhower. The county went Republican in every presidential election between 1968 and 1988, however, and in 1992 a plurality of the county's voters supported Republican George Bush over Democrat Bill Clinton and Ross Perot, the independent candidate. By the early 1980s there were only two communities in the county. Sterling City (population, 984) is the county's seat of government and the area's trade center; the other community is Broome.